Have any AI systems yet been developed that can knowingly lie to / deceive a human?
The Saturday Papers: Would AI Lie To You? is a blog post summarizing a research paper called Toward Characters Who Observe, Tell, Misremember, and Lie. This research paper details some researchers' plans to implement &quot;mental models&quot; for NPCs in video games. NPCs will gather information about the world, and convey that knowledge to other people (including human players). However, they will also &quot;misremember&quot; that knowledge (either &quot;mutating&quot; that knowledge or just forgetting about it), or even lie:

As a subject of conversation gets brought up, a character may convey false information—more precisely, information that she herself does not believe—to her interlocutor. Currently, this happens probabilistically according to a character’s affinity toward the interlocutor, and the misinformation is randomly chosen.

Later on in the research paper, they detailed their future plans for lying:

Currently, lies are only stored in the knowledge of characters who receive them, but we plan to have characters who tell them also keep track of them so that they can reason about past lies when constructing subse- quent ones. While characters currently only lie about other characters, we plan to also implement self-centered lying (DePaulo 2004), e.g., characters lying about their job titles or relationships with other characters. Finally, we envision characters who discover they have been lied to revising their affinities toward the liars, or even confronting them.

The research paper also detailed how other video game developers attempted to create lying NPCs, with an emphasis on how their system differs:

TALE-SPIN characters may lie to one another (Meehan 1976, 183-84), though rather arbitrarily, as in our current system implementation. GOLEM implements a blocks world variant in which agents deceive others to achieve goals (Castelfranchi, Falcone, and De Rosis 1998), while Mouth of Truth uses a probabilistic representation of character belief to fuel agent deception in a variant of Turing’s imitation game (De Rosis et al. 2003). In Christian (2004), a deception planner injects inaccurate world state into the beliefs of a target agent so that she may unwittingly carry out actions that fulfill ulterior goals of a deceiving agent. Lastly, agents in Reis’s (2012) extension to FAtiMA employ multiple levels of theory of mind to deceive one another in the party game Werewolf. While all of the above systems showcase characters who perceive—and in some cases, deceive—other characters, none appear to support the following key components of our system: knowledge propagation and memory fallibility. ...
Like a few other systems noted above, Dwarf Fortress also features characters who autonomously lie. When a character commits a crime, she may falsely implicate someone else in a witness report to a sheriff, to protect herself or even to frame an enemy. These witness reports, however, are only seen by the player; characters don’t give false witness reports to each other. They may, however, lie about their opinions, for instance, out of fear of repercussions from criticizing a leader. Finally, Dwarf Fortress does not currently model issues of memory fallibility—Adams is wary that such phenomena would appear to arise from bugs if not artfully expressed to the player.